Writing instrument having excellent cap-off performance

ABSTRACT

The writing instrument having an excellent cap-off performance is characterized, as shown in, for example, FIG.  3,  by that in a writing instrument  10  having a pen tip  13  comprising a fibrous feed or a plastic feed, the pen tip  13  described above is coated with a substance which is solid at room temperature and in which a solubility in an ink solvent is 10% or less at room temperature among substances providing the pen tip with a cap-off property. This writing instrument  10  is such excellent in a cap-off performance that the good writing performance is obtained even after the pen tip is left standing in the air over a long period of time.

TECHNICAL FIELD

The present invention relates to a writing instrument which has a goodwriting performance even after a pen tip is left standing in the air fora long period of time and which is excellent in a cap-off performance.

BACKGROUND ART

Writing instruments in which inks are penetrated into pen tipscomprising a fibrous feed or a plastic feed so as to write, such as amarking pen, a sign pen and a brush pen have so far been used in manycases.

However, when a cap is taken away to leave a pen tip part standing inthe air for long tome, there is involved the problem that the pen tippart is dried to cause inferior writing.

In the past, writing instruments such as a marking pen, a sign pen and abrush pen each having an excellent cap-off performance are obtained byadding to inks, additives such as higher fatty acid esters of specificpolyglycerin, specific acidic phosphoric acid higher alcohol esters andsalts thereof, specific phosphorous acid higher alcohol esters andspecific decaglycerin stearic acid esters each of which makes itpossible to inhibit vaporization (Japanese Patent Publication No. Sho62-34352 and Japanese Patent Application Laid-Open No. Sho 61-261380).

However, a large part of additives having a high vaporization-inhibitingeffect has a solubility of 10% by weight or less in solvents and has aproblem in terms of a low solubility. In particular, the solubility at0° C. is 5% by weight or less, and there are the problems that storageat a low temperature and repeating of low and high temperatures produceprecipitations of the additives described above in the inks and bringabout clogging in the ink passages to reduce the writing property ordeteriorate the cap-off property with the passage of time.

On the other hand, disclosed in Japanese Patent Application Laid-OpenNo. Hei 7-242094 is a dry-preventing method for a writing instrument inwhich in order to effectively inhibit an ink solvent from volatilizingfrom a writing part in a period of time passing until first writingafter producing the writing instrument to prevent inferior writing in anon-use state from being caused over a long period of time, one end partof a writing feed comprising a porous feed material is inserted into anink reservoir absorbing an ink prepared by dissolving a dye in solventsand the other end is formed in a writing part of the writing instrumentand in which a high boiling solvent such as benzyl alcohol having a slowvolatilizing speed among the ink solvents is coated on or impregnatedinto the writing part of the writing feed described above.

However, the dry-preventing method disclosed in this gazette has anobject to prevent drying in a period of time passing until first writingafter producing the writing instrument, and a target thereof is a highboiling solvent such as benzyl alcohol having a slow volatilizing speedamong the ink solvents, so that the writing part is not prevented frombeing dried after writing, and it is different from the presentinvention in terms of an object, an action and a structure (technicalidea). Further, benzyl alcohol used for the dry-preventing method for awriting instrument described above is liquid at room temperature andfreely miscible with solvents, and it has the problem that if it is leftstanding over a long period of time, it is introduced into the inkreservoir by diffusion of the solution and the effect is almost lost.Further, benzyl alcohol flows out by writing once, and therefore theeffect is not continued to be shown until the ink is exhausted.

Accordingly, the existing state is that in writing instruments such as amarking pen, a sign pen and a brush pen each having a pen tip comprisinga fibrous feed or a plastic feed, demanded are writing instruments whichhave a good preservability at a low temperature and in which a cap-offperformance is not deteriorated with the passage of time and thatdesired are writing instruments which do not bring about starving inwriting as well when the pen tip is left standing in the air over a longperiod of time by forgetting to put the cap and which provides anexcellent writing performance.

In light of the problems on the conventional techniques described above,the present invention intends to solve them, and an object thereof is toprovide a writing instrument which has a good preservability at a lowtemperature and does not cause clogging in an ink passage and whichprovides a good writing performance even after the pen tip is leftstanding in the air over a long period of time and is excellent in acap-off performance.

DISCLOSURE OF THE INVENTION

Intensive investigations of the problems of the conventional techniquesdescribed above repeated by the present inventors have resulted infinding that in order to obtain writing instruments such as a markingpen, a sign pen and a brush pen each having an excellent cap-offperformance, pen tips comprising a fibrous feed or a plastic feed whichare used for these writing instruments are coated with an additive whichis less liable to be dissolved in solvents and has avaporization-inhibiting effect, whereby a writing instrument meeting theobject described above can be obtained. Thus, they have come to completethe present invention.

That is, the writing instrument of the present invention having anexcellent cap-off performance comprises the following items (1) to (8).

(1) A writing instrument having an excellent cap-off performance,wherein in the writing instrument having a pen tip comprising a fibrousfeed or a plastic feed, the pen tip described above is coated with asubstance which is solid at room temperature and in which a solubilityin an ink solvent is 10% or less at room temperature and whichrepeatedly and constantly films on a surface part of the pen tip thatcan be broken by writing pressure in writing, among substances providingthe pen tip with a cap-off property.

(2) The writing instrument having an excellent cap-off performance asdescribed in the above item (1), wherein the coated substance has amelting point of 40 to 95° C.

(3) The writing instrument having an excellent cap-off performance asdescribed in the above item (1) or (2), wherein the coating substance isat least one selected from glycerin derivatives, alkylphosphoric acidesters, polyoxyethylenesorbitan fatty acid esters, polyoxyethylenesorbitfatty acid esters, paraffin wax, microcrystalline wax, polyolefin wax,pentaerythritol derivatives and lecithin.

(4) The writing instrument having an excellent cap-off performance asdescribed in any of the above items (1) to (3), wherein the amountcoated on the pen tip is 0.01 to 20% by weight in terms of a weightratio.

(5) The writing instrument having an excellent cap-off performance asdescribed in any of the above items (1) to (4), wherein a substancewhich is solid at room temperature and in which a solubility in an inksolvent is 0.01 to 10% at room temperature among substances providing acap-off property being added to an ink in the writing instrument and theadding amount of which is 0.01 to 10% by weight based on total amount ofthe ink.

(6) The writing instrument having an excellent cap-off performance asdescribed in any of the above items (1) to (5), wherein the substanceproviding a cap-off property which is added to the ink is at least oneselected from glycerin derivatives, alkylphosphoric acid esters,polyoxyethylenesorbitan fatty acid esters, polyoxyethylenesorbit fattyacid esters, paraffin wax, microcrystalline wax, polyolefin wax,pentaerythritol derivatives and lecithin.

(8) The writing instrument having an excellent cap-off performance asdescribed in any of the above items (1) to (6), being a direct liquidwriting instrument comprising an ink tank part which is a barrel fordirectly storing an ink and a collector member for temporarily reservingthe ink, wherein the ink is derived from the ink tank part to the pentip directly or via a feed.

(9) The writing instrument having an excellent cap-off performance asdescribed in any of the above items (1) to (6), being a writinginstrument having an ink reservoir absorbing an ink in a barrel, whereinthe ink is derived from the ink reservoir to the pen tip directly or viaa feed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) to (n) are explanatory drawings for explaining a structure ofthe pen tip comprising a fibrous feed according to the presentinvention, and FIGS. 2(a) to (j) are explanatory drawings for explaininga structure of the pen tip comprising a plastic feed according to thepresent invention.

FIG. 3 is an explanatory drawing showing one example by a crosssectional embodiment, in which the writing instrument of the presentinvention is applied to a direct liquid type writing instrument, andFIG. 4 is an explanatory drawing showing by a cross sectionalembodiment, one example in which the writing instrument of the presentinvention is applied to a writing instrument equipped with a valvemechanism.

FIGS. 5 and 6 are explanatory drawings each showing by a cross sectionalembodiment, examples of a type in which an ink is absorbed in an inkreservoir such as a sliver in the writing instrument of the presentinvention, and FIG. 7 is an explanatory drawing showing by a crosssectional embodiment, another example of a type in which an ink isabsorbed in an ink reservoir such as a sliver in the writing instrumentof the present invention.

FIG. 8 is an explanatory drawing showing by a cross sectionalembodiment, one example in which the writing instrument of the presentinvention is applied to a writing instrument of a knocking type.

FIG. 9 is an explanatory drawing showing the pen tip structure used inthe examples of the present invention and the comparative examples.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention shall be explained in more details with referenceto attached drawings.

The writing instrument having an excellent cap-off performance in thefirst embodiment of the present invention is characterized by that inthe writing instrument having a pen tip comprising a fibrous feed or aplastic feed, the pen tip described above is coated with a substancewhich is solid at room temperature and in which a solubility in an inksolvent is 10% or less at room temperature and which repeatedly andconstantly films on a surface part of the pen tip that can be broken bywriting pressure in writing, among substances providing the pen tip witha cap-off property.

The writing instrument having an excellent cap-off performance in thesecond embodiment of the present invention is characterized by that inthe writing instrument having a pen tip comprising a fibrous feed or aplastic feed, the pen tip described above is coated with a substancewhich has a melting point (mp) of 40 to 95° C. and in which a solubilityin an ink solvent is 10% or less at room temperature among substancesproviding the pen tip with a cap-off property.

Further, the writing instrument having an excellent cap-off performancein the third embodiment of the present invention is characterized bythat in the writing instrument having a pen tip comprising a fibrousfeed or a plastic feed, the pen tip described above is coated with asubstance which is solid at room temperature and has a melting point(mp) of 40 to 95° C. and in which a solubility in an ink solvent is 10%or less at room temperature among the substances providing the pen tipwith a cap-off property and that a substance which is solid at roomtemperature and in which a solubility in an ink solubility is 0.01 to10% at room temperature among the substances providing a cap-offproperty is added to the ink in the writing instrument.

The coating substance used in the first to third embodiments(hereinafter, these three embodiments shall be referred to merely as┌embodiment┘) of the present invention is a substance which is solid atroom temperature(25° C. or lower, the same shall apply hereinafter) andin which a solubility in an ink solvent is 10% or less, preferably 5% orless and more preferably 1% or less at room temperature among thesubstances providing a pen tip with a cap-off property. A lower limitvalue of the solubility includes 0% and is preferably 0.01% or more andmore preferably 0.1% or more.

Among the substances providing a pen tip with a cap-off property, thosewhich are liquid at room temperature or those in which a solubility inan ink solvent exceeds 10% at room temperature are eluted in an inksolvent by virtue of a dissolution or diffusion action and reduced in aneffect by storage over a long period of time or loses an effect as theink decreases by using the pen, so that they can not achieve the effectsof the present invention.

The term “the solubility in an ink solvent is 10% or less at roomtemperature” described above means that in the coating substance, asolubility in the ink solvent (a solvent comprising an organic solventwhich is an ink component described later) used in the present inventionis 10% or less at room temperature.

More preferred coating substance is a substance which has thecharacteristics described above, and among the substances providing thepen tip with a cap-off property, preferred are those having a meltingpoint (mp) of 40 to 95° C., preferably 50 to 85° C. and more preferably60 to 75° C.

In the writing instrument using the coating substance having a meltingpoint (mp) of 40 to 95° C., that is, the writing instrument of thesecond embodiment, more substance providing the pen tip with a cap-offproperty than required is not eluted in the ink and therefore a dryingtime of the drawn lines written on a non-absorbing face of glass isshortened.

The coating substance used in the embodiment of the present inventionshall not specifically be restricted as long as it has thecharacteristics described above, that is, the characteristics that it issolid at room temperature and has preferably a melting point of 40 to95° C. and that the solubility in an ink solvent is 10% or less at roomtemperature. It includes, for example, at least one or mixtures of twoor more kinds selected from glycerin derivatives such as diglycerinmonostearate, triglycerin monostearate, pentaglyceryl tristearate,hexaglyceryl tristearate and decaglycerin distearate, alkylphosphoricacid esters such as polyoxyethylene-stearyl phosphate,polyoxyethylenesorbitan fatty acid esters such aspolyoxyethylenesorbitan monostearate and polyoxyethylenesorbitantristearate, polyoxyethylenesorbit fatty acid esters such aspolyoxyethylenesorbit hexastearate, paraffin wax, microcrystalline wax,pentaerythritol derivatives such as pentaerythritol monostearate andpentaerythritol distearate, lecithin, saccharose esters, polyolefin wax,ascorbic acid stearate and sorbic acid stearate each having thecharacteristics described above.

Preferably, it is solid (more preferably having a melting point of 40 to95° C.) at room temperature and has a solubility of 10% or less in asolvent at room temperature. Further, from a viewpoint of a difficultyin allowing the substance providing a cap-off property to be dissociatedby physical friction at the pen tip and flow-out of the ink, preferredare diglycerin monostearate, pentaglyceryl tristearate,polyoxyethylene-stearyl phosphate, lecithin, paraffin wax,microcrystalline wax and polyolefin wax because the harder property andthe lower solubility elevates the durability and the effects.

The specific examples of various coating substances having thecharacteristics described above have been given as described above (fromdiglycerin monostearate to sorbic acid stearate). In the secondembodiment, selected are those in which a melting point (mp) falls in arange of 40 to 95° C. among these various coating substances.

In the embodiment of the present invention, a coating method for thesubstance providing a pen tip with a cap-off property and having thecharacteristics described above shall not specifically be restricted aslong as the amount required for allowing the effects of the presentinvention to be exhibited is coated on the pen tip comprising a fibrousfeed or a plastic feed. The substance having the characteristicsdescribed above can be coated by, for example, dissolving it in asolvent dissolving the above substance, subjecting the pen tip todipping treatment in or spraying treatment with it and then drying byheating or at room temperature. When the solubility is extremely low,the substance can be coated by dipping the pen tip in the heatedsolution thereof and cooling it.

These coating methods are excellent as a method which is easy andinexpensive.

The solvents for dissolving the substance having the characteristicsdescribed above include, for example, alcohols such as methyl alcohol,ethyl alcohol, n-propyl alcohol and isopropyl alcohol (i-propylalcohol), glycols such as ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether and propylene glycol monomethyl ether, ketonessuch as acetone and methyl ethyl ketone, esters such as methyl acetate,ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetateand propylene glycol monoethyl ether acetate, ethers such as dimethylether and diethyl ether, hydrocarbons such as hexane, heptane andmethylcyclohexane, and chlorinates compounds such as chloroform andmethylene chloride.

An amount of the substance having the characteristics described abovecoated on the pen tip is 0.01 to 20% by weight, preferably 0.1 to 10% byweight and more preferably 0.3 to 5% by weight in terms of a weightratio.

If the coating amount is less than 0.01% by weight, the effects of thepresent invention can not be achieved, and if it exceeds 20% by weight,the ink passage at the pen tip is not preserved, and the ink is hard tobe discharged, so that starving is caused or as writing goes on.Accordingly, it is not preferred.

In the embodiment of the present invention, a material, a structure anda production method of the pen tip used shall not specifically berestricted and include, for example, pen tips comprising fibrous feedsobtained by processing parallel fiber bundles comprising one or acombination of two or more kinds of natural fibers, animal hair fibers,polyacetal base resins, acryl base resins, polyester base resins,polyamide base resins, polyurethane base resins, polyolefin base resins,polyvinyl base resins, polycarbonate base resins, polyether base resinsand polyphenylene base resins and fiber bundles of felt and the like orfibrous feeds prepared by subjecting these fibrous feeds to processingwith resins, plastic feeds obtained by forming ink grooves in an axialdirection of the various plastic materials described above, and poroussubstances obtained by melting and bonding powders of the variousplastic powders described above. The forms thereof include optional onessuch as tabular substances, fiber-converged substances, sinteredsubstances and foamed substances.

A specific shape of the pen tip used comprising a fibrous feed includes,for example, those shown in FIG. 1 (a) to (n). Further, an embodiment ofthe ink groove at the pen tip comprising a plastic feed shown in FIG.2(a) in which an ink groove is formed in an axial direction of thevarious plastic materials described above includes, for example, thosehaving structures shown in FIG. 2(b) to (j).

In order to coat the pen tip with the substance having thecharacteristics described above to obtain the intended writinginstrument having an excellent cap-off performance, those havingpreferably a porosity of 30 to 75% and a slit size of about 1 to 20 μmare preferred when a fibrous feed is used for the pen tip, and thosehaving preferably an average slit size of 20 to 40 μm are preferred whena plastic feed is used for the pen tip. The porosity and slit sizedescribed above shall not be restricted to the value ranges describedabove as long as the object of the present invention can be achieved bycoating the pen tip with the substance having the characteristicsdescribed above.

Further, the slit size described above is calulated from the followingequation:

slit size=porosity×(radius of yarn)/(1−porosity)

Inks used for the writing instrument in the embodiment of the presentinvention shall not specifically be restricted as long as they haveoil-ink components usually used for a marking pen, a sign pen and abrush pen, and capable of being used are, for example, colorants,organic solvents, resins which can be dissolved in the above organicsolvents and other additives for a writing instrument.

The colorants include oil-soluble dyes and pigments, and almost all ofconventional oil-soluble dyes which can be dissolved in organic solventscan be used as the oil-soluble dyes. The dyes include, for example,Orazol Yellow 2GLN, Orazol Red 3GL, Orazol Blue 2GLN, Neonzapon BlueFLE, Spirit Black SP, Parifast Red 1308, Oil Blue BA, Oil Yellow 185,Oil Red TR71, Oil Black S, Victoria Blue, Rhodamine 6JHSA and FlexYellow 105, and the pigments shall not specifically be restricted andinclude, for example, azo base pigments, condensed polyazo basepigments, phthalocyanine base pigments, metal complex salt pigments,thioindigo pigments, dye lake pigments, organic pigments such asfluorescent pigments, carbon black, and inorganic pigments such astitanium oxide. Further, capable of being used as well are processedpigments the surfaces of which are processed by resin coating, forexample, various Microlys A types, AS Black, AS Blue and IK Red. Thesedyes and/or pigments can be used alone or in a mixture of two or morekinds thereof. A use amount thereof is different according to the kindof the colorant and the other ink components and is 1 to 30% by weight,preferably 2 to 15% by weight based on the total amount of the ink.

The organic solvents include lower alcohols such as ethyl alcohol,propyl alcohol and isopropyl alcohol, aromatic hydrocarbons such astoluene and xylene, lower aliphatic ketones such as methyl ethyl ketoneand methyl isobutyl ketone, lower alcohol esters of lower fatty acidssuch as ethyl acetate and butyl acetate, aliphatic hydrocarbons such ashexane and heptane, alicyclic hydrocarbons such as cyclohexane andethylcyclohexane, alkyl alcohols of glycols, and glycol ethers such aspropylene glycol monomethyl ether. They can be used alone or in amixture of two or more kinds thereof. A use amount thereof is 50 to 90%by weight, preferably 70 to 85% by weight based on the total amount ofthe ink.

A resin is used as a film-forming agent, a sticking agent onto a coatedface, a viscosity-controlling agent for the ink and a dispersant for thecolorant, and various natural resins and synthetic resins which have sofar been used can be used. It includes, for example, rosin, ester gums,rosin base such as maleic acid-modified rosin and phenol-modified rosin,cellulose base resins such as ethyl cellulose and nitrocellulose, vinylbase resins such as polyvinylbutyral and vinyl chloride-vinyl acetatecopolymer resins, petroleum base resins, ketone base resins, acryl baseresins, condensation products of aldehyde and urea and a maleic acidresin. They can be used alone or in a mixture of two or more kindsthereof. A use amount thereof is 0.1 to 30% by weight, preferably 1 to20% by weight based on the total amount of the ink.

Other additives for a writing instrument include, for example, anionic,nonionic and cationic surfactants, preservatives, fungicides, rustpreventives, lubricants and pH-controlling agents.

Substantially the same coating substances described above can be usedfor the ink additive providing a cap-off property used in the thirdembodiment of the present invention and include those which are solid atroom temperature and in which a solubility in the ink solvent is 0.01 to10%, preferably 0.01 to 5%, more preferably 0.1 to 4% and further morepreferably 0.1 to 3% at room temperature among the substances providingthe pen tip with a cap-off property.

Among the ink additives providing the pen tip with a cap-off property,those which are liquid at room temperature or those in which asolubility in the ink solvent exceeds 10% are eluted in the ink solventby virtue of a dissolution or diffusion action and reduced in furthereffect by storage over a long period of time or lose further effect asthe ink decreases by using the pen, and therefore they are notpreferred.

The term “a solubility in the ink solvent is 0.01 to 10% at roomtemperature” described above means that a solubility of the ink additivein the ink solvent (the solvent comprising an organic solvent which isthe ink component described above) is 0.01 to 10% at room temperature.

Among the ink additives providing a pen tip with a cap-off property,more preferred ink additives are those which have a melting point (mp)of 40 to 95° C., preferably 50 to 85° C. and more preferably 60 to 75°C. and in which a solubility in the ink solvent is 0.01 to 10%,preferably 0.01 to 5%, more preferably 0.1 to 4% and further morepreferably 0.1 to 3% at room temperature.

The ink additive used in the third embodiment of the present inventionshall not specifically be restricted as long as it has thecharacteristics described above, that is, the characteristics that it issolid at room temperature and has preferably a melting point of 40 to95° C. and that the solubility in the ink solvent is 0.01 to 10% at roomtemperature. It includes, for example, at least one or mixtures of twoor more kinds selected from glycerin derivatives such as diglycerinmonostearate, triglycerin monostearate, pentaglyceryl tristearate,hexaglyceryl tristearate and decaglycerin distearate, alkylphosphoricacid esters such as polyoxyethylene-stearyl phosphate,polyoxyethylenesorbitan fatty acid esters such aspolyoxyethylenesorbitan monostearate and polyoxyethylenesorbitantristearate, polyoxyethylenesorbit fatty acid esters such aspolyoxyethylenesorbit hexastearate, paraffin wax, microcrystalline wax,pentaerythritol derivatives such as pentaerythritol monostearate andpentaerythritol distearate, lecithin, saccharose esters, polyolefin wax,ascorbic acid stearate and sorbic acid stearate each having thecharacteristics described above.

Preferred are diglycerin monostearate, pentaglyceryl tristearate,polyoxyethylenestearyl phosphate and lecithin because they are solid(more preferably having a melting point of 40 to 95° C.) and have asolubility of 0.01 to 10% in a solvent at room temperature.

An amount of the ink additive having the characteristics described aboveadded to the ink is 0.01 to 10% by weight, preferably 0.05 to 5% byweight and more preferably 0.1 to 1% by weight ink in terms of a weightratio based on the total amount of the ink.

If the amount thereof added to the ink is less than 0.01% by weight,further effects of the present invention can not be achieved. On theother hand, if it exceeds 10% by weight, drying time of the drawn linesis delayed and storage over an extended period of time or repeating oflow and high temperatures produces precipitations in the ink and bringsabout clogging in the ink passage to reduce the writing property.Accordingly, it is not preferred.

In the writing instrument of the third embodiment of the presentinvention, the coating substance providing the pen tip with a cap-offproperty is coated, and the ink additive providing the pen tip with acap-off property is further added to the ink, so that it can furtherexhibit the effects of the present invention as compared with thewriting instrument of the first or second embodiment.

The structure of the writing instrument of the embodiment of the presentinvention shall not specifically be restricted as long as it is astructure having a pen tip comprising a fibrous feed or a plastic feedwhich is usually used for a marking pen, a sign pen and a brush pen, andit can be applied as well to a writing instrument having a cap for awriting instrument and a writing instrument having no cap for a writinginstrument.

In the embodiment of the present invention, capable of being achieved isthe writing instrument which provides a good writing performance evenafter the pen tip is left standing in the air for long time and isexcellent in a cap-off performance. It includes, for example, thestructures of the conventional writing instruments having a cap for awriting instrument shown in FIG. 3 to FIG. 7, the structures of amarking pen, a sign pen and a brush pen each having a simple sealingmechanism and the structures of a marking pen, a sign pen and a brushpen of a knocking type requiring no cap for a writing instrument shownin FIG. 8.

A direct liquid type writing instrument is shown in FIG. 3, and theabove direct liquid type writing instrument 10 has a structure in whichit has an ink tank part 11 which is a barrel for directly storing an inkwithout absorbing it in a sliver and an ink holder (collector member) 12for temporarily holding the ink so that the ink which is pushed out fromthe ink tank when air contained in the ink tank part 11 is expanded by arise in a temperature is prevented from dropping from the pen tip or theair vent is disposed in a front part of the ink tank part 11 and inwhich a pen tip 13 comprising a fibrous feed is disposed in a tip partof the collector member 12. The ink is introduced from the ink tank part11 into the pen tip 13 by introducing the ink from the ink tank part 11into the pen tip 13 via a feed 14 provided with an ink passage, which isdisposed in a central hole 12 a of the collector member 12.

In FIG. 3, a holder member is shown by 15; a rear barrel fixed to a rearpart of the ink tank part 11 is shown by 16; and a cap is shown by 17. Arear part of the pen tip 13 may be disposed directly in the ink tankpart 11 to introduce the ink without passing through the feed 14.

A writing instrument 20 shown in FIG. 4 is a valve type writinginstrument containing therein a steel ball 21 which is a stirring ball,and it has an ink tank part 22 which is a barrel for directly storing anink without absorbing the ink in a sliver and is constituted so that theink is fed to a pen tip 24 comprising a fibrous feed via a valvemechanism 23. In FIG. 4, a holder member is shown by 25; shown by 26 isa holder member which is interposed between the valve mechanism 23 andthe holder member 25 to hold a rear part of the pen tip 24; and a cap isshown by 27.

Writing instruments of a type in which an ink is absorbed in an inkreservoir such as a sliver are shown in FIG. 5 and FIG. 6. The aboverespective writing instruments 30 a, 30 b have ink reservoirs 32 a, 32 babsorbing inks in fibrous substances such as a sliver in barrel bodies31 a, 31 b which are barrels and are constituted so that rear end parts34 a, 34 b of pen tips 33 a, 33 b comprising fibrous feeds are broughtinto contact with front parts of the ink reservoirs 32 a, 32 b tothereby feed the inks contained in the ink reservoirs 32 a, 32 b, to thepen tips 33 a, 33 b. Plugs fixed to rear end parts of the barrel bodies31 a, 31 b are shown by 35 a, 35 b, and caps are shown by 36 a, 36 b. Adifference between the writing instruments shown in FIG. 5 and FIG. 6resides in that the shapes of the barrel bodies 31 a, 31 b and the pentips 33 a, 33 b and the structures of the plugs 35 a, 35 b are a littledifferent.

A writing instrument of a sign pen type in which an ink is absorbed inan ink reservoir such as a sliver as is the case with the writinginstrument shown in FIG. 5 is shown in FIG. 7. The above writinginstrument 40 has an ink reservoir 42 absorbing an ink in a fibroussubstance such as a sliver in a barrel body 41 which is a barrel and isconstituted so that a rear end part 43 a of a pen tip 43 comprising aplastic feed is brought into contact with a front part of the inkreservoir 42 to thereby feed the ink contained in the ink reservoir 42to the pen tip 43. A plug fixed to a rear end part of the barrel body 41is shown by 44; a holder member is shown by 45; and a cap is shown by46.

Shown in FIG. 8 is a knocking type writing instrument of a sign pen typerequiring no cap in which an ink is absorbed in an ink reservoir such asa sliver. The above writing instrument 50 is equipped with an internalbarrel having an ink reservoir 52 absorbing an ink in a fibroussubstance such as a sliver in a barrel body 51 and is constituted sothat a rear end part 54 a of a pen tip 54 comprising a fibrous feed isbrought into contact with a front part of the ink reservoir 52 tothereby feed the ink contained in the ink reservoir 52 to the pen tip54. A knocking part mounted to a rear end part of the barrel 51 is shownby 55, and it is constituted so that the pen tip 54 comes out of thebarrel body 51 to fall in a writing state by pushing out the aboveknocking part forward and that the pen tip 54 is received in the barrelbody 51 by operating a releasing button 55 a.

In the writing instrument of the present invention which is constitutedin such manner as described above, the pen tip comprising a fibrous feedor a plastic feed is coated with the respective substances describedabove which are solid at room temperature and has preferably a meltingpoint of 40 to 95° C. and in which a solubility in the solvent is 10% orless at room temperature among the substances providing the pen tip witha cap-off property, whereby a very fragile film can be formed on asurface part of the pen tip, and this film prevents the solvent which isa volatile component contained in an ink from vaporizing. Further, theabove film is broken by writing pressure in writing to make writingpossible. In addition, the substance providing a cap-off property coatedon the pen tip is dissolved again, though formation of the above film isa little different depending on the coating amount described above, inthe ink by a required amount, and next time when the pen tip is exposedto the air, a new film is formed on a pen tip surface by virtue ofinteraction with the ink solvent. This procedure of filmformation→writing→film formation →writing - - - is repeated many timesto constantly show the effect.

Accordingly, the writing instrument of the present invention shows suchan excellent cap-off performance that a good writing performance isachieved even after the pen tip is left standing in the air for longtime. Further, the substance providing a cap-off property is notcontained in the ink components, so that the preservability at a lowtemperature is good, and clogging is not caused in the ink passage.

In the writing instrument of the second embodiment, more substanceproviding the pen tip with a cap-off property than required is noteluted in the ink, and therefore drying time of the drawn lines writtenon a non-absorbing face of glass is shortened.

Further, in the writing instrument of the third embodiment, the coatingsubstance providing the pen tip with a cap-off property is coated, andthe ink additive providing the pen tip with a cap-off property isfurther added to the ink in an addition amount in which the writingperformance is not deteriorated, so that a synergistic effect in whichthe effects of the writing instruments of the first embodiment and thesecond embodiment are multiplied synergistically is exhibited, that is,the cap-off performance is such further excellent that further betterwriting performance is achieved even after the pen tip is left standingin the air for long time (these points shall be described in detailswith reference to examples).

It is a matter of course that the writing instrument of the presentinvention shall not be restricted to the embodiments described above andthat they can be changed to various forms as long as the scope of thepresent invention is not changed.

The writing instrument of the present invention shall not be restrictedto, for example, a direct liquid type writing instrument in which theink of the embodiment described above is directly stored withoutabsorbing it in a sliver, a writing instrument equipped with a valvemechanism and a writing instrument in which an ink is absorbed in an inkreservoir such as a sliver. It shall not specifically be restricted aslong as the pen tip comprising a fibrous feed or a plastic feed iscoated with various substances having the characteristics describedabove or the ink additive providing a cap-off performance is added tothe ink, and it can be applied as well to, for example, brush pens,cartridge type pens and applicators for cosmetics.

In particular, the writing instrument which provides a good writingperformance even after the pen tip is left standing in the air for longtime with the cap off and which is excellent in a cap-off performancecan be achieved in the present invention, and therefore it can suitablybe used for writing instruments having structures of a marking pen, asign pen and a brush pen of a knocking type requiring no cap.

EXAMPLES

The present invention shall be explained in further details withreference to examples and comparative examples, but the presentinvention shall not be restricted to the following examples.

Examples 1 to 14 and Comparative Examples 1 to 4 and 6 to 11

A pen tip shown in FIG. 9 was used as the pen tip. A making pen (inkamount: 4.5 g) prepared by installing this pen tip into a writinginstrument shown in FIG. 5 was used.

The pen tip was a fibrous feed comprising a sliver of acryl fibers, andused was one having a weight of 0.19 g, a length of 37 mm and a diameterof 4.0 mm (porosity: about 60%).

Used as the coating substances (agents) were (1) hexaglyceryltristearate (melting point: 57° C.), (2) polyoxyethylenesorbitanmonostearate (melting point: 53° C.), (3) polyoxyethylenestearylphosphate (melting point: 56° C.), (4) microcrystalline wax (meltingpoint: 67° C., ┌Hi-Mic-2045┘ manufactured by Nippon Seiro Co., Ltd.) and(5) paraffin wax (melting point: 61° C., ┌Paraffin Wax 140┘ manufacturedby Nippon Seiro Co., Ltd.).

The solubilities of the substances (1) to (5) described above in an inksolvent (solvent comprising ethyl alcohol, n-propyl alcohol, i-propylalcohol and propylene glycol monomethyl ether) were 0.4% in (1), 9% in(2), 0.1% in (3), 0.1% or less in (4) and 0.1% or less in (5).

The coating substance of the prescribed amount described above wasdissolved in methylene chloride which was a solvent, and the pen tipcomprising a fibrous feed described above was dipped in the solutionprepared above and heated at 50° C. for one hour. Then, it was leftstanding at room temperature a night and then poured into a mesh-shapedvessel to remove the solvent. Next, the pen tip was dried at roomtemperature for one hour, at 50° C. for 3 hours and at room temperaturefor 3 hours to prepare a sample, and assembled was a marking pen (inkamount: 4.5 g) in which the above pen tip was installed into the writinginstrument shown in FIG. 5. This marking pen was used to carry out thefollowing tests.

The coating amount was shown by a difference in a weight of the pen tipbetween before and after treating which corresponded to an amount of thecoating agent of (1) to (5) described above adhered to the pen tip, andit was shown by weight % based on the weight of the pen tip beforeprocessing. Those having treating rates of 1%, 2% and 3% were used inthe examples.

Inks (1) to (10) comprising compositions shown in the following Table 1were used for the inks.

Comparative Example 5

The same ones as those in Examples 1 to 14 and Comparative Examples 1 to4 and 6 to 11 were used for the pen tips and the marking pens which werethe use members.

The pen tip was treated by dipping the pen tip comprising a fibrous feeddescribed above in benzyl alcohol (melting point: −15.5° C.), and thenthe above pen tip was installed in a writing instrument shown in FIG. 5immediately so that benzyl alcohol was not dried to assemble a markingpen (ink amount: 4.5 g). The coating amount was about 0.2 g, thoughscattered because of scattering in drying benzyl alcohol and a shape ofthe pen tip. This assembled marking pen was left standing at roomtemperature for a day and then used to carry out the following tests.

TABLE 1 Ink composition Ink composition (1) (2) (3) (4) (5) (6) (7) (8)(9) (10) Ethyl alcohol 75.0  — 74.0 — 74.0  — 74.6  — 73.6  — n-Propylalcohol — 14.0 — 14.0  — 14.0  — 14.0  — 14.0  i-Propyl alcohol 7.5 —7.5 — 7.5 — 7.5 — 7.5 — Propylene glycol monomethyl ether — 70.0 — 68.0 — 68.0  — 69.8  — 68.8  Laropearl A101*¹ — 12.0 — 12.0  — 12.0  — 12.0 — 12.0  Alresat KM400*² 10.0  — 10.0 — 10.0  — 10.0  — 10.0  — VictoriaBlue BSA*³ 2.5  3.0 2.5 3.0 2.5 3.0 2.5 3.0 2.5 3.0 Rhodamine 6JHSA*⁴2.5  1.0 2.5 1.0 2.5 1.0 2.5 1.0 2.5 1.0 Flex Yellow 105*⁵ 2.5 — 2.5 —2.5 — 2.5 — 2.5 — Hexaglyceryl tristearate*⁶ — — 1.0 — — 0.4 — 0.4 —Polyoxyethylenesorbitan monostearate*⁷ — — — 2.0 — — — — — —Polyoxyethylenestearyl phosphate*⁸ — — — — — — — 0.2 — 0.2Microcrystalline wax*⁹ — — — — 1.0 — — — 1.0 — Paraffin wax*¹⁰ — — — — —2.0 — — — 1.0 (wt %) *¹Condensation product of aldehyde and urea(manufactured by BASF Co., Ltd.) *²Maleic acid resin (manufactured byHoechst Co., Ltd.) *³Dye (manufactured by Zeneca Co., Ltd.) *⁴Dye(manufactured by Zeneca Co., Ltd.) *⁵Dye (manufactured by Zeneca Co.,Ltd.) *⁶Coating agent (1) (cap-off performance-providing ink additive)*⁷Coating agent (2) (cap-off performance-providing ink additive)*⁸Coating agent (3) (cap-off performance-providing ink additive)*⁹Coating agent (4) (cap-off performance-providing ink additive,[Hi-Mic-2045]) *¹⁰Coating agent (5) (cap-off performance-providing inkadditive, [Paraffin Wax 140])

The marking pens obtained in Examples 1 to 14 and Comparative Examples 1to 11 were used to carry out evaluation of a writing performance, acap-off test after storing at a low temperature, a cap-off test afterwriting, a drawn line-drying test and overall evaluation.

These results are shown in the following Table 2 and Table 3.

Cap-off Test

The caps of the respective marking pens were taken off, and the writingperformances at 25° C. based on a change in a cap-off time with thepassage of time (one hour to one month) were measured according to thefollowing evaluation criteria. When the evaluation is ⊚ even after oneday or longer passes, preferably 3 day or longer pass, it shows that thecap-off performance is excellent.

Evaluation Criteria

⊚: writable without starving

◯: slightly starving at the beginning of writing

Δ: starving in the first line

▴: starving in the second line

×: unwritable

Cap-off Test After Storing at a Low Temperature

The respective marking pens were left standing at 0° C. for 24 hours andthen slowly returned to room temperature in one day. The caps were takenoff as was the case with the writing performance evaluation describedabove to compare the writing performances based on a change in a cap-offtime with the passage of time with the evaluation results at 25° C.described above and evaluate them according to the following evaluationcriteria.

⊚: same as the cap-off performance at 25° C. before storing at a lowtemperature

◯: cap-off performance is a little reduced as compared with the cap-offperformance at 25° C. before storing at a low temperature

×: cap-off performance is notably reduced as compared with the cap-offperformance at 25° C. before storing at a low temperature

Cap-off Test After Writing

The respective marking pens were used for writing in 100 m under anenvironment of 25° C. Then, the caps were taken off as was the case withthe cap-off test described above to compare the writing performances at25° C. based on a change in a cap-off time with the passage of time withthe evaluation results at 25° C. described above and evaluate themaccording to the following evaluation criteria.

⊚: same as before writing (the cap-off performance at 25° C.)

◯: cap-off performance is a little reduced as compared with beforewriting (the cap-off performance at 25° C.)

×: cap-off performance is notably reduced as compared with beforewriting (the cap-off performance at 25° C.)

Drawn Line-drying Test

The respective marking pens were used for writing on glass (20×20×0.5cm) under an environment of 25° C. to determine time passing until thewritten lines were completely dried by touching with a finger. In thedrawn line-drying property, time of 30 seconds or shorter means good(◯); time of 10 seconds or shorter means very good (⊚); and time ofexceeding 30 seconds means the deteriorated (×) drawn line-dryingproperty.

Overall Evaluation

The cap-off test, the cap-off test after storing at a low temperature,the cap-off test after writing and the drawn line-drying test eachdescribed above were taken into overall consideration and evaluatedoverall according to the following criteria.

Evaluation Criteria

⊚: satisfying all items

◯: cap-off test after writing is not a little satisfactory, but theother items are satisfied

Δ: cap-off test and drawn line-drying test are satisfactory, but theother items are unsatisfactory

×: cap-off test and drawn line-drying test are unsatisfactory

TABLE 2 Cap-off performance evaluation results Writing performanceevaluation based on Cap-off test Cap-off Pen Ink kind change in cap-offtime with passage of time after storing test Drawn Overall Exam- feed in1 2 8 1 3 1 2 3 1 at a low after line-drying evalu- ple kind Table 1hour hours hours day days week weeks weeks month temperature writingproperty ation 1 A Ink (1) ⊚ ⊚ ⊚ ⊚ ◯ Δ ▴ X X ⊚ ◯ 5 seconds ◯ 2 B Ink (1)⊚ ⊚ ⊚ ⊚ ⊚ Δ ▴ X X ⊚ ◯ 5 seconds ◯ 3 C Ink (1) ⊚ ⊚ ⊚ ◯ Δ ▴ X X X ⊚ ◯ 5seconds ◯ 4 D Ink (1) ⊚ ⊚ ⊚ ⊚ ⊚ ◯ Δ ▴ X ⊚ ◯ 5 seconds ◯ 5 E Ink (2) ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ◯ 10 seconds  ◯ 6 F Ink (1) ⊚ ⊚ ⊚ ⊚ ◯ Δ ▴ X X ⊚ ◯ 5seconds ◯ 7 G Ink (1) ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ▴ X X ⊚ ◯ 5 seconds ◯ 8 H Ink (1) ⊚ ⊚⊚ ⊚ ⊚ Δ ▴ X X ⊚ ◯ 5 seconds ◯ 9 I Ink (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ 10seconds  ◯ 10  G Ink (7) ⊚ ⊚ ⊚ ⊚ ◯ Δ ▴ X X ⊚ ⊚ 5 seconds ⊚ 11  H Ink (7)⊚ ⊚ ⊚ ⊚ ⊚ ◯ ▴ X X ⊚ ⊚ 5 seconds ⊚ 12  I Ink (7) ⊚ ⊚ ⊚ ⊚ ⊚ Δ ▴ X X ⊚ ⊚ 5seconds ⊚ 13  G Ink (8) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ 10 seconds  ⊚ 14  H Ink(8) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ 10 seconds  ⊚ Pen feed kind: A: coating agent(1), treating rate 1% fibrous feed B: coating agent (1), treating rate2% fibrous feed C: coating agent (1), treating rate 3% fibrous feed D:coating agent (2), treating rate 1% fibrous feed E: coating agent (3),treating rate 1% fibrous feed F: coating agent (4), treating rate 1%fibrous feed G: coating agent (4), treating rate 2% fibrous feed H:coating agent (4), treating rate 3% fibrous feed I: coating agent (5),treating rate 2% fibrous feed

TABLE 3 Cap-off performance evaluation results Com- Writing performanceevaluation based on Cap-off test Cap-off parative Pen Ink kind change incap-off time with passage of time after storing test Drawn Overall Exam-feed in 1 2 8 1 3 1 2 3 1 at a low after line-drying evalu- ple kindTable 1 hour hours hours day days week weeks weeks month temperaturewriting property ation 1 a Ink (1) X X ◯ X 5 seconds X 2 a Ink (3) ◯ ◯ Δ▴ X X X X 5 seconds X 3 a Ink (2) Δ ▴ X X ◯ X 5 seconds X 4 a Ink (4) ⊚⊚ ◯ ◯ Δ ▴ X X X X 2 minutes X or longer 5 b Ink (2) Δ Δ X X ◯ X 2minutes X or longer 6 a Ink (5) ◯ Δ X X X X 10 seconds X 7 a Ink (6) ⊚ ⊚⊚ ⊚ ⊚ ⊚ Δ X X X X 10 seconds Δ 8 a Ink (7) ⊚ ⊚ ⊚ Δ X X X X 5 seconds Δ 9a Ink (8) ⊚ ⊚ ⊚ ⊚ ⊚ Δ X X X X X 2 minutes X or longer 10  a Ink (9) ⊚ ⊚⊚ ⊚ Δ X X X X 5 seconds Δ 11  a Ink (10) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ X X 10seconds Δ Pen feed kind: a: not treated b: high boiling solvent (benzylalcohol) dipping-treated, fibrous feed

As apparent from the results shown in Table 2 and Table 3 describedabove, it has been confirmed that the marking pens prepared by coatingthe pen tips of the present invention obtained in Examples 1 to 14 withthe vaporization inhibitors have good writing performances even afterexposing the pen tips to the air over a long period of time and showgood results on the cap-off test after storing at a low temperature ascompared with the marking pens in which the pen tips falling outside thepresent invention obtained in Comparative Examples 1 to 11 are notcoated with the vaporization inhibitors.

To specifically observe the examples, obtained in Examples 1 to 9 arethe marking pens prepared by coating the pen tips with the vaporizationinhibitors having different melting points, and obtained in Examples 10to 14 are the writing instruments prepared by coating the pen tips withthe coating substances providing the pen tip with a cap-off property andadding the ink additives providing a pen tip with a cap-off property tothe inks.

In particular, it has been found that the writing instruments preparedby coating the pen tips with the coating substances providing the pentip with a cap-off property and adding the ink additives providing thepen tip with a cap-off property to the inks, which were obtained inExamples 10 to 14 are such excellent in a cap-off performance thatfurther better writing performance is obtained even after the pen tipsare left standing in the air for long time as compared with the writinginstruments obtained in Examples 1 to 9.

In contrast with this, observing Comparative Examples 1 to 11, the pentips were not coated with the vaporization inhibitors in ComparativeExamples 1 and 3, and ordinary components were used for the inkcomponents. It can be found that in these cases, writing was impossiblein 2 hours and 8 hours respectively after the caps were taken off.

Further, in Comparative Examples 2 and 4 and Comparative Examples 6 to11, the vaporization inhibitors were dissolved in the ink componentswithout coating the pen tips with the vaporization inhibitors. It hasbeen found that the cap-off performances were a little improved ascompared with those in Comparative Examples 1 and 3, but theperformances both in the cap-off tests after storing at a lowtemperature and after writing were reduced and that the drawnline-drying properties were deteriorated as well in Comparative Examples4 or 9.

Further, the pen tip which was subjected to conventional high boilingsolvent (benzyl alcohol)-dipping treatment was used in ComparativeExample 5, and it has been found that the cap-off performance was notgood as well in this case and that the performances in the cap-off testsafter storing at a low temperature and after writing were reduced andthe drawn line-drying property was deteriorated as well.

INDUSTRIAL APPLICABILITY

As described above, the writing instrument according to the presentinvention has an excellent writing property even after the pen tip isleft standing in the air over a long period of time, and it has a stablequality and is excellent in a cap-off performance with the passage oftime.

In the writing instruments in which the pen tips are coated with thecoating substances having a melting point of 40 to 95° C. and providingthe pen tips with a cap-off property, more coating substances providingthe pen tips with a cap-off property than required are not eluted in theinks, and therefore a drying time of the drawn lines written on anon-absorbing face of glass is shortened.

Further, in the writing instruments prepared by coating the pen tip withthe coating substances providing the pen tip with a cap-off property andadding the ink additives providing the pen tips with a cap-off propertyto the inks, the cap-off performance is such further excellent thatfurther better writing performance is achieved even after the pen tipsare left standing in the air for long time.

What is claimed is:
 1. A writing instrument having an excellent cap-offperformance, wherein the writing instrument having a pen tip comprisinga fibrous feed or a plastic feed, the pen tip described above is coatedwith a substance which is solid at room temperature and in which asolubility in an ink solvent is 10% or less at room temperature andwhich repeatedly and constantly films on a surface part of the pen tipthat can be broken by writing pressure in writing, among substancesproviding the pen tip with a cap-off property.
 2. The writing instrumenthaving an excellent cap-off performance as described in claim 1, whereinthe coated substance has a melting point of 40 to 95° C.
 3. The writinginstrument having an excellent cap-off performance as described in claim1, wherein the coating substance is at least one selected from glycerinderivatives, alkylphosphoric acid esters, polyoxyethylenesorbitan fattyacid esters, polyoxyethylenesorbit fatty acid esters, paraffin wax,microcrystalline wax, polyolefin wax, pentaerythritol derivatives andlecithin.
 4. The writing instrument having an excellent cap-offperformance as described in claim 1, wherein the amount coated on thepen tip is 0.01 to 20% by weight in terms of a weight ratio.
 5. Thewriting instrument having an excellent cap-off performance as describedin claim 1, wherein a substance which is solid at room temperature andin which a solubility in an ink solvent is 0.01 to 10% at roomtemperature among the substances providing a cap-off property is addedto an ink in the writing instrument and the adding amount of which is0.01 to 10% by weight based on total amount of the ink.
 6. The writinginstrument having an excellent cap-off performance as described in claim5, wherein the substance providing a cap-off property which is added tothe ink is at least one selected from glycerin derivatives,alkylphosphoric acid esters, polyoxyethylenesorbitan fatty acid esters,polyoxyethylenesorbit fatty acid esters, paraffin wax, microcrystallinewax, polyolefin wax, pentaerythritol derivatives and lecithin.
 7. Thewriting instrument having an excellent cap-off performance as describedin claim 1, being a direct liquid writing instrument comprising an inktank part which is a barrel for directly storing an ink and a collectormember for temporarily reserving the ink, wherein the ink is derivedfrom the ink tank part to the pen tip directly or via a feed.
 8. Thewriting instrument having an excellent cap-off performance as describedin claim 1, being a writing instrument having an ink reservoir absorbingan ink in a barrel, wherein the ink is derived from the ink reservoir tothe pen tip directly or via feed.